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Question
Expand the following:
(−6x − 7y)2
Sum
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Solution
(−6x − 7y)2
Using the identity:
(a + b)2 = a2 + 2ab + b2
Here, (−6x − 7y)2 = [−(6x + 7y)]2 = (6x + 7y)2
So, let a = 6x, b = 7y
(6x + 7y)2 = (6x)2 + 2(6x) (7y) + (7y)2
= 36x2 + 2(42xy) + 49y2
∴ (6x + 7y)2 = 36x2 + 84xy + 49y2
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Chapter 3: Expansions - MISCELLANEOUS EXERCISE [Page 39]
